An ultraviolet (UV) reactor may be used to disinfect water by rendering bacteria harmless or to energize oxidants to reduce total organic carbon (TOC). In certain applications, the UV reactor includes baffle plates to provide plug flow with respect to inlet water so as to maximize the exposure time of the water to UV radiation. Plug flow may be defined as flow across the entire cross section of a vessel that is within a small velocity range. However, a desirable plug flow is not met by many available reactors due to the design of the baffle plates.
FIG. 1 depicts a computational fluid dynamics (CFD) study which shows flow vectors for a conventional reactor. FIG. 1 will be described in conjunction with selected elements of a conventional reactor. Water 10 enters an inlet pipe 12 and flows through a UV chamber 14 at a much higher velocity than a targeted plug flow velocity. Due to the configuration of the reactor, the water flows around a side of a tank 16 and subsequently exits through an outlet pipe 18. Flows along a side wall of the tank 16 are not desirable as they have a strong tendency to create a short circuit path as shown by arrow 20 in FIG. 1. A short circuit path may be defined as passage through the UV chamber 14 at a velocity that is much higher than a desired plug velocity. Thus, a substantial portion of the water in the UV chamber 14 is not subjected to sufficient UV energy.
In FIG. 1, areas A, B, C and D depict velocities of greater than approximately 14.25, 0.75, 0.75 and 3.75 in/s, respectively, that exist in a conventional reactor, thus indicating that desirable plug flow does not exist. In addition, it has been determined that conventional reactors may have a velocity profile which exceeds 7 in/s which is known to be an undesirably high flow velocity for a UV reactor.